1. Field of the invention
The present invention relates to a rear wheel suspension controller having means of adjusting vehicle height and changing suspension characteristic by detecting bumps and dips of the road surface during vehicle running.
2. Prior art
In the past, the suspension controllers of this kind were proposed in the published unexamined patent applications Sho-57-172808, Sho-59-23713 and Sho-59-23712. Such controllers detect the vehicle height and the acceleration of vertical movement by a vehicle height sensor, and judge as `bad road condition` if the detected value exceeds a predetermined value for a certain period of time. After that, the vehicle height is raised to improve the feel of the ride and to prevent the vehicle bottom from contacting the road surface.
In the conventional controllers, however, the vehicle height is changed only in the case that the vehicle continues running on a bad road for a certain period, in other words, the vehicle height is not changed when the vehicle is tranversing a joint of the road or a sporadic bump or dip. Because of this, when a rear wheel passes the sporadic bump or dip after a front wheel has passed it, the vehicle bottom may come in contact with the road surface by the rear vehicle height vibration. In addition, when the vehicle height is kept low by the conventional control when the vehicle is running on a rough rod, the shortening of the shock absorber reaches its limit to bottom out, whereby the strong vibration is directly transmitted to the vehicle body via the shock absorber, which results in degrading the comfort of the ride.